In rational homotopy theory, the Halperin conjecture concerns the Serre spectral sequence of certain fibrations. It is named after the Canadian mathematician Stephen Halperin.
Suppose that is a fibration of simply connected spaces such that is rationally elliptic and (i.e., has non-zero Euler characteristic), then the Serre spectral sequence associated to the fibration collapses at the page. [1]
As of 2019, Halperin's conjecture is still open. Gregory Lupton has reformulated the conjecture in terms of formality relations. [2]